wiki:ElbatTOF2017

Version 41 (modified by Michael, 4 years ago) (diff)

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SVN: ​http://gauss.bu.edu/svn/tof-system/

ExampleTestPage?

Two experiments:

Meetings

HVPulser Rev A testing 1/16/20

Setup: The attached photo shows the setup used for testing the HVPulser. The BASYS3 FPGA connects to the ToF Adapter across its onboard PMOD connectors. The ToF adapter board then connects to the HVPulser with a DB15 cable. The ToF Adapter is supplied with +5V, -6V, and +3.3V on an 8 pin mini-fit jr connector, these voltages are also carried across the DB15 to the HVPulser. The ToF Adapter is also supplied with a switching voltage on a 2 pin mini fit jr connector. Nominally this switching voltage is -200V but for this round of testing -20V was supplied. Image (http://gauss.bu.edu/svn/tof-system/Gallery/2020-01-16/Testing_Setup.jpg)?

  • under these conditions the 5V supply drew ~250mA, the -6V supply drew ~200mA, and the 3.3V supply drew <10mA. No load was placed across the output of the HVPulser so the -20V switching supply drew no current.

Control Signals: Using test points on the ToF Adapter the wave forms for the positive end of the HV_pos and HV_neg ECL signals were captured Image (http://gauss.bu.edu/svn/tof-system/Gallery/2020-01-16/HV_POS+.jpg)? Image (http://gauss.bu.edu/svn/tof-system/Gallery/2020-01-16/HV_NEG+.jpg)?. These signals fit the expectations of ECL logic standards.

The HV_pos signal is used to control the High-Gate (connected to output and ground) of the switching circuit and the HV_neg signal is used to control the Low-Gate (connected to output and switching voltage 'nominally -200v') of the switching circuit. When the high gate is on the output swings to ground and when the low gate is on the output swings to the switching voltage. the switching of the HV_pos and hv_neg signals can then be used to swing the output. These two pictures show the control signals displayed above and output waveform to demonstrate this. Image (http://gauss.bu.edu/svn/tof-system/Gallery/2020-01-16/HV_out_and_pos.jpg)? Image (http://gauss.bu.edu/svn/tof-system/Gallery/2020-01-16/HV_out_and_neg.jpg)?

The HV_on signal is used to control a fixed current supply on the HVPulser. The current supply supplies ~3mA but this can be changed by adjusting the value of R14 (resistor connected to collector of NPN Q2). The current can be calculated by dividing 1.5V by the value of R14. The effect of this current supply will be discussed in the output section of this write up.

For this test signals were run at a 1Mhz frequency clock on the FPGA. The HV_on signal was fixed at logic 1. The HV_pos signal was held at logic 0 and set to logic 1 for 1us every 8us. The HV_neg signal was held at logic 1 and set to logic 0 for 1us every 8us. This table demonstrates the test waveform.

Time (us)12345678
HV_on11111111
HV_pos00001000
HV_neg10111111
  • Note: the HV_neg signal is inverted. A logic 0 for HV_pos activates the Low-Gate and switches the output to the supply voltage. A logic 1 for HV_pos closes this gate. for sake of clarity here are control truth tables for the signals.
HV_posHigh Gate
0OFF
1ON


HV_negLow Gate
0ON
1OFF


HV_onCurrent Supply
0OFF
1ON
  • It is critically important that at no point both gates are active in order to protect the HVPulser PCB from over current. this means at no point should HV_neg be a logic 0 while HV_pos is a logic 1. All other conditions are safe.

Output: The following wave form was captured from the output of the HVPulser --HV_out.png-- The output rests at 0V and switches to the supply voltage as expected. During testing the supply voltage was changed from -20V to -30V and the low end of the output moved 1:1 with the supply to -30V. The output was recored with a 100ns rise time and a 50ns fall time. --HV_out_rising.jpg-- --HV_out_falling.jpg--

PCB Update 1/9/20

  • LV Mixer: Board is assembled but not yet tested.
  • HV Mixer: Fix footprints for U2 (FRM-0505S) & U3 (IK1212SA), oriented upside down
    -NOTE: U11 and U10 are inverting (UCC27518), Edit the schematic and footprint to reflect this.
    -U8 (SI8610EC-B-IS) was assumed to be an inverter but it is not.
    -Swap R14(3K) for a 470Ohm resistor to fix current supplied to current sink. R14 is on emitter pin of Q2 (SMMBTA92L)
    -current supply(HV_ON) in original design supplies ~7mA, this has to do with current draw from clamping diodes not present in the revision of the design, look into adding this component to the circuit and seeing how it affects the output waveform.
  • ToF Adapter: Board is assembled with the need for some changes.
    -Fix footprint for U6 and U8 (SN74LVCG04), pads are too far apart and too large. It was still possible to solder but there is concerning clearance.
    -Fix footprint for U2 (MC100EPT25), footprint is too small. It was not possible to attach this component but this segment of the circuit is not immediately needed for testing. Possible temporary solutions could be dead-bugging the proper component to the back of the board or using another IC and dead-bugging that.
    -Look into removing 3.3V power supply and generating 3.3V from linear regulator
    -Move to female connectors
    -Shift connectors and make more room for BNC connectors
  • Filament Supply: Parts have arrived, still waiting for PCB to arrive.
    -Switch pins 2 and 3 on footprint U1E (LM6144)
  • Pre-Amp: PCB design up for review.
  • Firmware: Switch pin mapping to correspond with pin mismatch in U9 (10H124) on ToF Adapter
  • ALL:
    -Fix Testpoint footprints (move to 1/10")

PCB Documentation

Rev A boards ordered Dec 2019:

The following boxes/instruments need to be constructed for Xuetao in 2019:

Regular Helium

Metastable Helium

  • TOF box (pulse output only, no detector readout) NewTOFBox
    • Trigger signal out to TDC
  • Filament PS for Exciter (? not sure) ~1A for indirectly heated cathode NewFilamentSupply (one fil. end is at Cathode potential)
    • Can be same supply as for regular helium e-gun, pulsed at 200V
  • 200V bias supply for HV pulser
  • HV pulser (Bill's design with transformers) NewHVPulser
    • Update design if needed ("high-side" FET drivers?)

Older version of list for BU

  • TOF box
    • FPGA board with pseudo-random pulser and TDC; controlled via USB/serial I/F
    • Pulse input from detector preamp (also supplies preamp power)
    • 0..-25V manually adjustable supply for cathode offset (with panel meter)
  • Filament supply
    • Isolated supply, 0-3A constant current (?)
  • HV Pulser / Mixer
  • LV Pulser / Mixer
  • Preamp (MCP)
  • Preamp (Channeltron)
  • E-Gun power supply

On 5/30/19, Michael visited. He says only the first 4 boxes are needed. Xuetao will not use the Channeltron because he has a huge MCP.

For the "Regular" experiment, we use the MCP preamp and LV pulser

For the "Metastable" experiment, we use the Channeltron preamp and HV pulser

Photos (by board/box):

Photos (raw):